The proliferation of the wireless telecommunications into every sector of business and all facets of personal life and daily activity have far exceeded any initial projections. Wireless communication has become a staple for conducting business in many industries and represents a significant portion of all telecommunications. As wireless communication, and the devices which enable it, become more widely integrated into everyday activities, the demand for wireless service coverage greatly expands.
Wireless subscribers and wireless service providers often rely upon band amplifiers to expand and extend wireless coverage. For example, an in-building amplifier can be installed to increase signal reception and transmission for wireless subscribers in a particular office facility. Most wireless communication amplifiers are bidirectional and thus have capability of amplifying both uplink and downlink wireless signals such that both the reception to the subscriber and the transmission to the base station are improved.
Wireless amplifiers can be used in a variety of implementations, including providing extended service areas directly to wireless subscribers and amplifying signals passing between nodes in a wireless network. For example, wireless bidirectional amplifiers can be used to amplify signals passing between two parts of the wireless system, such as the base station and local service area. As the subscriber demand for wireless services increases, the necessity for inexpensive, efficient, and reliable equipment to provide that service increases.
In the past, wireless communication systems were often covered by one frequency band. Therefore, the wireless bidirectional amplifiers used in these systems were only required to process one frequency band. FIG. 1 shows a conventional single band bidirectional amplifier 105. The conventional single band bidirectional amplifier 105 includes an uplink amplifier 120 and a downlink amplifier 115. The uplink amplifier 120 processes the signals received from the service antenna, antenna 135, to be transmitted via the base antenna 130. Similarly, the downlink amplifier 115 processes the signals received from the base antenna, antenna 130, to be transmitted via the service antenna, antenna 135. Duplexers are provided to pass the transmitted and received signals of the amplifier 105. For example, a signal received at antenna 130 is passed to duplexer 110 and likewise the duplexer 110 passes a signal to be transmitted to antenna 130. The duplexer 110 passes transmission signal, Tx1, through its TX11 filter to the input port of the downlink amplifier 115. The duplexer 110 also receives the received signal, Rx1, through its RX11 filter from the output port of the uplink amplifier 120. Similarly, duplexer 125 passes the uplink signal received from antenna 135 to the input port of the uplink amplifier 120 and passes the downlink signal received from downlink amplifier 115 to antenna 135 for transmission to the service area.
Unlike the single band systems, more modern wireless telecommunication networks transmit signals over multiple frequency bands. To provide signal coverage for systems operating in two frequency bands, dual band bidirectional amplifiers were designed. Conventional dual band bidirectional amplifiers are constructed from two single band bidirectional amplifiers, such as 105, connected by two power dividers. FIG. 2 provides an illustration of a conventional dual band bidirectional amplifier 200. The two single band bidirectional amplifiers, 205 and 210, are provided as the central components of bidirectional amplifier 200. Two power dividers, 215 and 220, provide signal path for the two frequency bands transmitted and received by antenna 225 and antenna 230 into the bidirectional amplifiers 205 and 210.
Similar to the amplifier shown in FIG. 1, the first single band bidirectional amplifier 205 includes a duplexer 235, a downlink amplifier 240, an uplink amplifier 245, and a duplexer 250. The duplexer 235 passes transmission signal, Tx1, through its TX11 filter to the input port of the downlink amplifier 240. The duplexer 235 also receives the amplified uplink signal, Rx1, through its RX11 filter from the output port of the uplink amplifier 245. Similarly, duplexer 250 passes the uplink signal, Rx1, through its RX21 filter received from power divider 220 to the input port of the uplink amplifier 245 and passes the amplified downlink signal, Tx1, through its TX21 filter received from downlink amplifier 240 to power divider 220 for transmission via antenna 230.
The second single band bidirectional amplifier 210 is provisioned in a manner similar to that of the first single band bidirectional amplifier 205, such that it includes a duplexer 255, a downlink amplifier 260, an uplink amplifier 265, and a duplexer 270. The duplexers, 255 and 270, pass the received and transmitted signals to the appropriate amplifier, 260 or 265.
While suitable for its intended purposes, the conventional dual band bidirectional amplifier 200 depicted in FIG. 2 suffers from a number of drawbacks. Significantly, the addition of the power dividers, 215 and 220, to the circuit inserts a large amount of loss and noise into the amplifier device. For example, in one embodiment the system gain for the dual band bidirectional amplifier 200 is 6 dB lower than in the single band bidirectional amplifier 100 configuration due to the additional loss of the power dividers, 215 and 220. Furthermore, in that embodiment the power dividers, 215 and 220, reduce the output power by 3 dB and increase the noise figure by 3 dB. An additional drawback to the dual band bidirectional amplifier 200 depicted in FIG. 2 relates to the cost of the device. As illustrated in FIG. 2, the dual band amplifier 200 configuration involves more than double the components of the single band amplifier 100 configuration; thus, the cost of the dual band amplifier 200 is more than double. As with any network element, cost is a large factor and one that can potentially be implementation prohibitive with respect to wireless telecommunication systems.
To overcome the drawbacks associated with designs like the dual band bidirectional amplifier 200, amplifiers were designed in an attempt to limit power loss and cost of the device. FIG. 3 is an illustration of an improved dual band bidirectional amplifier 300 as described in U.S. Pat. No. 6,993,286. The dual band bidirectional amplifier 300 is capable of amplifying signals in two frequency bands from antenna 305 and antenna 345 with only one amplifier chain. More particularly, whereas the dual band bidirectional amplifier 200 shown in FIG. 2 required two downlink amplifiers, 240 and 260 and two uplink amplifiers, 245 and 265, the dual band bidirectional amplifier 300 shown in FIG. 3 requires only one downlink amplifier 320 and one uplink amplifier 325.
In FIG. 3, downlink signals, are received at the base antenna 305. These downlink signals are passed to a first circulator 310. The circulator 310 is responsible for distributing the downlink signals to the appropriate duplexer. It also passes the uplink signals to transmit at the base antenna 305.
Duplexer 312 is configured to pass the uplink signal, Rx1, and downlink signal, Tx1, in the first frequency band. It routes the downlink signal, Tx1, from circulator 310 to the input port of downlink amplifier 320 via T-cable 313. It also routes the amplified uplink signal Rx1, from the output port of uplink amplifier 325 via T-cable 317 to circulator 310. Duplexer 315, on the other hand, is configured to pass the uplink signal, Rx2, and downlink signal, Tx2, in the second frequency band. It routes downlink signal, Tx2, from circulator 310 to the input port of downlink amplifier 320 via T-cable 313. It also routes the amplified uplink signal, Rx2, from output port of uplink amplifier 325 via T-cable 317 to circulator 310.
As illustrated in the FIG. 3, on the service side of the device, the duplexers, 330, works similarly to Duplexer 312. It is configured to pass the uplink signal, Rx1, and downlink signal, Tx1 of the first frequency band. It routes the uplink signal, Rx1, from circulator 340 to the input port of uplink amplifier 325 via T-cable 329. It also routes the amplified downlink signal Tx1, from the output port of downlink amplifier 320 via T-cable 327 to circulator 340. Duplexer 335, on the other hand, works similarly to Duplexer 315. It is configured to pass the uplink signal, Rx2, and downlink signal, Tx2, in the second frequency band. It routes uplink signal, Rx2, from circulator 340 to the input port of uplink amplifier 325 via T-cable 329. It also routes the amplified downlink signal, Tx2, from output port of downlink amplifier 320 via T-cable 327 to circulator 340.
T-cable 313, and other similar T-cables in the device, 329, combine the signals from both frequency bands to be amplified by either the downlink amplifier 320 or the uplink amplifier 325. T-cable 317 and 327 feed the amplified signals of both frequency bands to respective duplexers, 312, 315, 330 and 335.
Circulator 340 passes the first frequency downlink signal, Tx1, with the second frequency downlink signal, Tx2, for transmission via antenna 345. It also distributes the first and second frequency uplink signals, Rx1 and Rx2, received from antenna 345 and routes them to the appropriate duplexer, either 330 or 335.
Dual band bidirectional amplifier 300 improves upon the design of previous dual band amplifiers by implementing a single wide band bidirectional amplifier chain having only one uplink amplifier 325 and one downlink amplifier 320. The wide band bidirectional amplifier chain is capable of amplifying both of the frequency bands of the system.
The design of dual band bidirectional amplifier 300 exhibits some superior characteristics in comparison to the design of dual band bidirectional amplifier 200. Due to the elimination of the power dividers, the dual band bidirectional amplifier 300 inserts less power loss and gain loss into the system. For example, in some implementations the output power of the dual band bidirectional amplifier 300 is 2 dB higher than the output power of dual band bidirectional amplifier 200. Additionally, the dual band bidirectional amplifier 300 exhibits improved sensitivity in comparison to other designs such as the dual band bidirectional amplifier 200. Furthermore, the dual band bidirectional amplifier 300 costs less than other designs due in large part to the face that it only requires one amplifier chain.
While the design of band amplifiers, such as dual band bidirectional amplifier 300, have been successful at overcoming some of the limitations and drawbacks of previous designs, there are some drawbacks that have been unaddressed. These unaddressed drawbacks are magnified by the increasing complexity of wireless telecommunication systems, especially if the systems operate with more than two frequency bands.
Therefore a need exists for a system or method that will address the limitations and drawbacks of the prior art band amplification devices.
Additionally, a need exists for a system or method to provide efficient band amplification in dual band wireless telecommunication systems.
Additionally, a need exists for a system or method to provide efficient band amplification in triple band wireless telecommunication systems.
Furthermore, a need exists to reduce system complexity and provide a cost effective device and power efficient device to band amplification in triple band wireless telecommunication systems.